I've clearly forgotten to do something with the gui on 9.3 because /var/etc/private/passdb.tdb did not get updated with a new user. The symptoms were an immediate fail when trying to access a private share. I fixed the problem manually via the shell by issuing "pdbedit -a fribble" where fribble was the name of a local user. I'm sure that this is normally done via the GUI - what did I forget to do?